1. Field of the Invention
This invention relates to waste oil recovery systems and in particular a waste oil recovery system for used oil filters.
2. Prior Art
Disposal of used oil filters has long been a problem for the entire automotive service and repair industry, which is a widely dispersed industry located throughout the world. The problem of oil filter disposal is the same, whether the oil filter is used for an engine on an automobile, truck, utility vehicle, or tractor. Currently, when an oil filter is removed from an engine there is substantial oil left in the oil filter, which will not drain via gravity. The reason the oil in the oil filter will not just drain out when the removed filter is positioned so that the openings on the filter are pointed downward is that in many oil filters there is a one way valve in the filter, which must be overcome by positive oil pressure. The one way valve ensures that there is oil pressure that the oil pressure gauge can detect. Normally oil pressure is at least 4 pounds per square inch when an engine is idling. The one way valve is not always present in oil filters and depends on the manufacturer. In some cases the positive pressure is provided for in the engine in another way, but there is still a problem, if just gravity is relied upon, in completely draining the oil from a used oil filter even when there is not a one way valve in the oil filter.
Oil filters currently are an environmental hazard and require special disposal, because of the oil left in the oil filter. The special disposal requirements are rather expensive and certainly inconvenient. In addition, because the oil is not completely removed from the oil filters, handling is at best a messy proposition, because handlers are never sure that additional oil will not drip out of the oil filter. Disposal would be simplified if the waste oil in the used oil filters could be completely removed before disposal. Then possibly the oil filters could be handled as normal waste and in any event they would be much easier to handle. Another advantage is that the recovered oil could possibly be recycled for use. When the number of oil filters changed daily is considered, the recovered oil could be significant.